1. Field of the Invention
The invention relates to a method and a device for contactless detection of edge structures of a test specimen, it being possible for the light quantity, which can be varied by means of the test specimen, of a light source to be measured and for the edge structures of the test specimen to be represented on the basis of the measurement of light quantity.
2. Discussion of the Prior Art
A device for detecting semiconductor housing, for example, is known from European reference EP 0 196 514. The edges of the semiconductor housings are projected by means of a microscope onto an image matrix of a CCD image converter. The CCD image converter converts the image focused onto its image matrix into individual electric charges which are then read out in rows and digitized in the fashion of pixels. The brightness values of the pixels are stored by row and column and conditioned to form space coordinates of the edges to be found.
A disadvantage of the known device resides in that the device, operating on the principle of image processing for detecting simple structures such as, for example, edges is very complicated, and therefore expensive. Moreover, this device is sensitive to extraneous light.
It is an object of the invention to provide a remedy to this problem. The invention achieves the object of avoiding the disadvantages of the known device, and of using simple means to create a device for detecting simple edge structures.
One aspect of the present invention resides in a method for contactless detection of edge structures of a test specimen, which method includes the steps of arranging a light source opposite a diaphragm, moving the test specimen over the diaphragm to vary a quantity of light transiting the diaphragm from the light source, measuring the varying light quantity which depends on the edge structure of the test specimen, and determining the edge structures of the test specimen from the transiting light quantity. Another aspect of the invention resides in a device for detecting edge structures of the specimen, which device includes a light source, means for detecting a light quantity of the light source, which light quantity can be varied by the test specimen, means for evaluating the variable light quantity, and a diaphragm arranged between the light source and the evaluating means so that the light quantity is fed to the evaluating means.
The advantages achieved by means of the invention are to be seen essentially in the fact that the detection of the edge structures is simplified. The bodies with the structures to be detected can be moved through the measuring zone with the aid of a simple, automated movement, the edge structures being detected during the movement. Due to the simple design of the measuring device and to the simple measuring method, the automatic system required and serving the purpose of automatic production can be of simple design. The serial production of the bodies with the edge structures (specimens) to be detected can be improved in terms of quality and production with the aid of the proposed device. Furthermore, the proposed measuring device is cost-effective and independent of extraneous light, and has an accuracy comparable with a device operating on the principle of image processing.
The invention is explained in more detail below with the aid of drawings representing an exemplary embodiment.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.